mirror of
https://github.com/openssl/openssl.git
synced 2024-12-27 06:21:43 +08:00
89f66fe2bc
CLA: trivial Reviewed-by: Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com> Reviewed-by: Richard Levitte <levitte@openssl.org> (Merged from https://github.com/openssl/openssl/pull/5473)
325 lines
9.2 KiB
Plaintext
325 lines
9.2 KiB
Plaintext
=pod
|
|
|
|
=head1 NAME
|
|
|
|
EVP_MD_CTX_new, EVP_MD_CTX_reset, EVP_MD_CTX_free, EVP_MD_CTX_copy_ex,
|
|
EVP_MD_CTX_ctrl, EVP_DigestInit_ex, EVP_DigestInit, EVP_DigestUpdate,
|
|
EVP_DigestFinal_ex, EVP_DigestFinalXOF, EVP_DigestFinal,
|
|
EVP_MD_CTX_copy, EVP_MD_type, EVP_MD_pkey_type, EVP_MD_size,
|
|
EVP_MD_block_size, EVP_MD_CTX_md, EVP_MD_CTX_size,
|
|
EVP_MD_CTX_block_size, EVP_MD_CTX_type, EVP_md_null,
|
|
EVP_get_digestbyname, EVP_get_digestbynid,
|
|
EVP_get_digestbyobj - EVP digest routines
|
|
|
|
=head1 SYNOPSIS
|
|
|
|
#include <openssl/evp.h>
|
|
|
|
EVP_MD_CTX *EVP_MD_CTX_new(void);
|
|
int EVP_MD_CTX_reset(EVP_MD_CTX *ctx);
|
|
void EVP_MD_CTX_free(EVP_MD_CTX *ctx);
|
|
void EVP_MD_CTX_ctrl(EVP_MD_CTX *ctx, int cmd, int p1, void* p2);
|
|
|
|
int EVP_DigestInit_ex(EVP_MD_CTX *ctx, const EVP_MD *type, ENGINE *impl);
|
|
int EVP_DigestUpdate(EVP_MD_CTX *ctx, const void *d, size_t cnt);
|
|
int EVP_DigestFinal_ex(EVP_MD_CTX *ctx, unsigned char *md, unsigned int *s);
|
|
int EVP_DigestFinalXOF(EVP_MD_CTX *ctx, unsigned char *md, size_t len);
|
|
|
|
int EVP_MD_CTX_copy_ex(EVP_MD_CTX *out, const EVP_MD_CTX *in);
|
|
|
|
int EVP_DigestInit(EVP_MD_CTX *ctx, const EVP_MD *type);
|
|
int EVP_DigestFinal(EVP_MD_CTX *ctx, unsigned char *md, unsigned int *s);
|
|
|
|
int EVP_MD_CTX_copy(EVP_MD_CTX *out, EVP_MD_CTX *in);
|
|
|
|
int EVP_MD_type(const EVP_MD *md);
|
|
int EVP_MD_pkey_type(const EVP_MD *md);
|
|
int EVP_MD_size(const EVP_MD *md);
|
|
int EVP_MD_block_size(const EVP_MD *md);
|
|
|
|
const EVP_MD *EVP_MD_CTX_md(const EVP_MD_CTX *ctx);
|
|
int EVP_MD_CTX_size(const EVP_MD *ctx);
|
|
int EVP_MD_CTX_block_size(const EVP_MD *ctx);
|
|
int EVP_MD_CTX_type(const EVP_MD *ctx);
|
|
|
|
const EVP_MD *EVP_md_null(void);
|
|
|
|
const EVP_MD *EVP_get_digestbyname(const char *name);
|
|
const EVP_MD *EVP_get_digestbynid(int type);
|
|
const EVP_MD *EVP_get_digestbyobj(const ASN1_OBJECT *o);
|
|
|
|
=head1 DESCRIPTION
|
|
|
|
The EVP digest routines are a high level interface to message digests,
|
|
and should be used instead of the cipher-specific functions.
|
|
|
|
=over 4
|
|
|
|
=item EVP_MD_CTX_new()
|
|
|
|
Allocates and returns a digest context.
|
|
|
|
=item EVP_MD_CTX_reset()
|
|
|
|
Resets the digest context B<ctx>. This can be used to reuse an already
|
|
existing context.
|
|
|
|
=item EVP_MD_CTX_free()
|
|
|
|
Cleans up digest context B<ctx> and frees up the space allocated to it.
|
|
|
|
=item EVP_MD_CTX_ctrl()
|
|
|
|
Performs digest-specific control actions on context B<ctx>.
|
|
|
|
=item EVP_DigestInit_ex()
|
|
|
|
Sets up digest context B<ctx> to use a digest B<type> from ENGINE B<impl>.
|
|
B<type> will typically be supplied by a function such as EVP_sha1(). If
|
|
B<impl> is NULL then the default implementation of digest B<type> is used.
|
|
|
|
=item EVP_DigestUpdate()
|
|
|
|
Hashes B<cnt> bytes of data at B<d> into the digest context B<ctx>. This
|
|
function can be called several times on the same B<ctx> to hash additional
|
|
data.
|
|
|
|
=item EVP_DigestFinal_ex()
|
|
|
|
Retrieves the digest value from B<ctx> and places it in B<md>. If the B<s>
|
|
parameter is not NULL then the number of bytes of data written (i.e. the
|
|
length of the digest) will be written to the integer at B<s>, at most
|
|
B<EVP_MAX_MD_SIZE> bytes will be written. After calling EVP_DigestFinal_ex()
|
|
no additional calls to EVP_DigestUpdate() can be made, but
|
|
EVP_DigestInit_ex() can be called to initialize a new digest operation.
|
|
|
|
=item EVP_DigestFinalXOF()
|
|
|
|
Interfaces to extendable-output functions, XOFs, such as SHAKE128 and SHAKE256.
|
|
It retrieves the digest value from B<ctx> and places it in B<len>-sized <B>md.
|
|
After calling this function no additional calls to EVP_DigestUpdate() can be
|
|
made, but EVP_DigestInit_ex() can be called to initialize a new operation.
|
|
|
|
=item EVP_MD_CTX_copy_ex()
|
|
|
|
Can be used to copy the message digest state from B<in> to B<out>. This is
|
|
useful if large amounts of data are to be hashed which only differ in the last
|
|
few bytes.
|
|
|
|
=item EVP_DigestInit()
|
|
|
|
Behaves in the same way as EVP_DigestInit_ex() except it always uses the
|
|
default digest implementation.
|
|
|
|
=item EVP_DigestFinal()
|
|
|
|
Similar to EVP_DigestFinal_ex() except the digest context B<ctx> is
|
|
automatically cleaned up.
|
|
|
|
=item EVP_MD_CTX_copy()
|
|
|
|
Similar to EVP_MD_CTX_copy_ex() except the destination B<out> does not have to
|
|
be initialized.
|
|
|
|
=item EVP_MD_size(),
|
|
EVP_MD_CTX_size()
|
|
|
|
Return the size of the message digest when passed an B<EVP_MD> or an
|
|
B<EVP_MD_CTX> structure, i.e. the size of the hash.
|
|
|
|
=item EVP_MD_block_size(),
|
|
EVP_MD_CTX_block_size()
|
|
|
|
Return the block size of the message digest when passed an B<EVP_MD> or an
|
|
B<EVP_MD_CTX> structure.
|
|
|
|
=item EVP_MD_type(),
|
|
EVP_MD_CTX_type()
|
|
|
|
Return the NID of the OBJECT IDENTIFIER representing the given message digest
|
|
when passed an B<EVP_MD> structure. For example, C<EVP_MD_type(EVP_sha1())>
|
|
returns B<NID_sha1>. This function is normally used when setting ASN1 OIDs.
|
|
|
|
=item EVP_MD_CTX_md()
|
|
|
|
Returns the B<EVP_MD> structure corresponding to the passed B<EVP_MD_CTX>.
|
|
|
|
=item EVP_MD_pkey_type()
|
|
|
|
Returns the NID of the public key signing algorithm associated with this
|
|
digest. For example EVP_sha1() is associated with RSA so this will return
|
|
B<NID_sha1WithRSAEncryption>. Since digests and signature algorithms are no
|
|
longer linked this function is only retained for compatibility reasons.
|
|
|
|
=item EVP_md_null()
|
|
|
|
A "null" message digest that does nothing: i.e. the hash it returns is of zero
|
|
length.
|
|
|
|
=item EVP_get_digestbyname(),
|
|
EVP_get_digestbynid(),
|
|
EVP_get_digestbyobj()
|
|
|
|
Returns an B<EVP_MD> structure when passed a digest name, a digest B<NID> or an
|
|
B<ASN1_OBJECT> structure respectively.
|
|
|
|
=back
|
|
|
|
=head1 RETURN VALUES
|
|
|
|
=over 4
|
|
|
|
=item EVP_DigestInit_ex(),
|
|
EVP_DigestUpdate(),
|
|
EVP_DigestFinal_ex()
|
|
|
|
Returns 1 for
|
|
success and 0 for failure.
|
|
|
|
=item EVP_MD_CTX_ctrl()
|
|
|
|
Returns 1 if successful or 0 for failure.
|
|
|
|
=item EVP_MD_CTX_copy_ex()
|
|
|
|
Returns 1 if successful or 0 for failure.
|
|
|
|
=item EVP_MD_type(),
|
|
EVP_MD_pkey_type(),
|
|
EVP_MD_type()
|
|
|
|
Returns the NID of the corresponding OBJECT IDENTIFIER or NID_undef if none
|
|
exists.
|
|
|
|
=item EVP_MD_size(),
|
|
EVP_MD_block_size(),
|
|
EVP_MD_CTX_size(),
|
|
EVP_MD_CTX_block_size()
|
|
|
|
Returns the digest or block size in bytes.
|
|
|
|
=item EVP_md_null()
|
|
|
|
Returns a pointer to the B<EVP_MD> structure of the "null" message digest.
|
|
|
|
=item EVP_get_digestbyname(),
|
|
EVP_get_digestbynid(),
|
|
EVP_get_digestbyobj()
|
|
|
|
Returns either an B<EVP_MD> structure or NULL if an error occurs.
|
|
|
|
=back
|
|
|
|
=head1 NOTES
|
|
|
|
The B<EVP> interface to message digests should almost always be used in
|
|
preference to the low level interfaces. This is because the code then becomes
|
|
transparent to the digest used and much more flexible.
|
|
|
|
New applications should use the SHA-2 (such as L<EVP_sha256(3)>) or the SHA-3
|
|
digest algorithms (such as L<EVP_sha3_512(3)>). The other digest algorithms
|
|
are still in common use.
|
|
|
|
For most applications the B<impl> parameter to EVP_DigestInit_ex() will be
|
|
set to NULL to use the default digest implementation.
|
|
|
|
The functions EVP_DigestInit(), EVP_DigestFinal() and EVP_MD_CTX_copy() are
|
|
obsolete but are retained to maintain compatibility with existing code. New
|
|
applications should use EVP_DigestInit_ex(), EVP_DigestFinal_ex() and
|
|
EVP_MD_CTX_copy_ex() because they can efficiently reuse a digest context
|
|
instead of initializing and cleaning it up on each call and allow non default
|
|
implementations of digests to be specified.
|
|
|
|
If digest contexts are not cleaned up after use
|
|
memory leaks will occur.
|
|
|
|
EVP_MD_CTX_size(), EVP_MD_CTX_block_size(), EVP_MD_CTX_type(),
|
|
EVP_get_digestbynid() and EVP_get_digestbyobj() are defined as
|
|
macros.
|
|
|
|
EVP_MD_CTX_ctrl() sends commands to message digests for additional configuration
|
|
or control.
|
|
|
|
=head1 EXAMPLE
|
|
|
|
This example digests the data "Test Message\n" and "Hello World\n", using the
|
|
digest name passed on the command line.
|
|
|
|
#include <stdio.h>
|
|
#include <openssl/evp.h>
|
|
|
|
main(int argc, char *argv[])
|
|
{
|
|
EVP_MD_CTX *mdctx;
|
|
const EVP_MD *md;
|
|
char mess1[] = "Test Message\n";
|
|
char mess2[] = "Hello World\n";
|
|
unsigned char md_value[EVP_MAX_MD_SIZE];
|
|
int md_len, i;
|
|
|
|
if (argv[1] == NULL) {
|
|
printf("Usage: mdtest digestname\n");
|
|
exit(1);
|
|
}
|
|
|
|
md = EVP_get_digestbyname(argv[1]);
|
|
if (md == NULL) {
|
|
printf("Unknown message digest %s\n", argv[1]);
|
|
exit(1);
|
|
}
|
|
|
|
mdctx = EVP_MD_CTX_new();
|
|
EVP_DigestInit_ex(mdctx, md, NULL);
|
|
EVP_DigestUpdate(mdctx, mess1, strlen(mess1));
|
|
EVP_DigestUpdate(mdctx, mess2, strlen(mess2));
|
|
EVP_DigestFinal_ex(mdctx, md_value, &md_len);
|
|
EVP_MD_CTX_free(mdctx);
|
|
|
|
printf("Digest is: ");
|
|
for (i = 0; i < md_len; i++)
|
|
printf("%02x", md_value[i]);
|
|
printf("\n");
|
|
|
|
exit(0);
|
|
}
|
|
|
|
=head1 SEE ALSO
|
|
|
|
L<dgst(1)>,
|
|
L<evp(7)>
|
|
|
|
The full list of digest algorithms are provided below.
|
|
|
|
L<EVP_blake2b512(3)>,
|
|
L<EVP_md2(3)>,
|
|
L<EVP_md4(3)>,
|
|
L<EVP_md5(3)>,
|
|
L<EVP_mdc2(3)>,
|
|
L<EVP_ripemd160(3)>,
|
|
L<EVP_sha1(3)>,
|
|
L<EVP_sha224(3)>,
|
|
L<EVP_sha3_224(3)>,
|
|
L<EVP_sm3(3)>,
|
|
L<EVP_whirlpool(3)>
|
|
|
|
=head1 HISTORY
|
|
|
|
EVP_MD_CTX_create() and EVP_MD_CTX_destroy() were renamed to
|
|
EVP_MD_CTX_new() and EVP_MD_CTX_free() in OpenSSL 1.1.0.
|
|
|
|
The link between digests and signing algorithms was fixed in OpenSSL 1.0 and
|
|
later, so now EVP_sha1() can be used with RSA and DSA.
|
|
|
|
EVP_dss1() was removed in OpenSSL 1.1.0.
|
|
|
|
=head1 COPYRIGHT
|
|
|
|
Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.
|
|
|
|
Licensed under the OpenSSL license (the "License"). You may not use
|
|
this file except in compliance with the License. You can obtain a copy
|
|
in the file LICENSE in the source distribution or at
|
|
L<https://www.openssl.org/source/license.html>.
|
|
|
|
=cut
|